JPS63123434A - Ash sorter - Google Patents

Abstract

Apparatus is provided for withdrawing a stream of relatively static bed material 26 from an operating fluidized bed reactor 10 and gravity feeding it through a conduit 42,46 to an exterior classifying chamber 57 into which a downward flow of air is introduced. The airflow is turned in the classifier 57 to move in an upward direction countercurrent to the flow of bed material. The velocity of the air is such that coarse bed material passes downwardly through the airflow and accumulates in the classifying chamber 57, while the fines are entrained in the upwardly moving airflow and both air and fines are introduced into the fluidized bed reactor 10.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an ash classifier for use in combination with a fluidized bed reactor.

BACKGROUND OF THE INVENTION Fluidized bed reactors are a known means for heat generation and are used in the field of chemical or metallurgical and other material processing for drying, roasting, calcining, and drying solids with gas. It can be used in various forms for incineration and heat treatment.

These gases are also used to supply high-temperature gases such as steam, to drive generators, as process heat, and for space heating and other purposes.

Typically, a fluidized bed reactor consists of a vessel equipped with a substantially horizontal air distribution plate or constriction plate that supports a bed of granular solids within the reaction chamber and that also controls the reaction chamber. It is separated from the wind box below the distribution plate.

Combustion air is introduced into the wind box and passed through an air distribution plate in sufficient quantities to provide a gas velocity that expands or fluidizes the solids bed, suspending the particulate solids in the bed in the flowing air stream and displacing the individual fluids. gives continuous random motion to . A fluidized bed resembles a boiling liquid in its appearance and properties. Conducting combustion reactions in fluidized beds has important advantages, including more uniform bed temperatures, combustion at relatively low temperatures, and high heat transfer rates.

Combustion of solid fuels such as coal involves vaporization of the organic components of the fuel, leaving behind solid ash particles. The finest ash particles are gas-scrubbed by the gas flowing through the reactor and discharged together with the waste gas through the stack. If most of the larger size ash particles improve the operation of the fluidized bed by retaining heat and contacting and igniting new fuel particles, these become part of the fluidized bed. Become.

Due to the high temperature of the fluidized bed and the continuous movement of ash particles within the fluidized bed, a large number of particles collide in a softened state due to the high temperature. In this condition, the ash easily aggregates and the agglomerates grow to such a size that they can no longer be fluidized and fall to the bottom of the fluidized bed and rest on the air distribution plate.

The accumulation of large ash particles and large ash agglomerates on the air distribution plate will eventually result in deflow of the fluidized bed and the operation must be shut down and the unfluidized accumulated ash removed.

[Summary of the Invention] The above problems have been recognized for some time. Various methods and devices have been proposed to improve this situation.

The purpose of the present invention is to provide a simple but effective method for removing too coarse ash particles and too large ash aggregates from the fluidized bed while returning the fine particles to the fluidized bed and maintaining the fluidized state of the fluidized bed. It is about providing the means.

That is, the ash classifier system of the present invention consists of a vessel located outside the fluidized bed reactor, which separates carrier particles, including ash aggregates and fine ash particles, in the air stream, and separates coarse particles. and agglomerates, and return fine ash particles and combustion air to the fluidized bed.

The ash classifier system comprises an ash vessel connected to a fluidized bed reactor by a conduit system. A sloped conduit is provided to remove fluidized bed material from the bottom of the fluidized bed by gravity. The inclined conduit connects to a vertical classifier conduit into which the fluidized bed material is delivered.

The vertical conduit extends downwardly through the top of the ash container and is located below the top wall of the ash container and above the bottom wall. The vertical conduit also extends above the junction with the inclined conduit to a level above the bed of the fluidized bed in the fluidized bed reactor. At the highest point of the vertical conduit, this conduit connects to an elbow or bend, and to this elbow a downwardly sloping conduit that passes through the fluidized bed reactor wall. A downwardly sloping conduit is connected to a fluidized bed reactor wall return port at a point in the reactor just above the bed surface of the expanded fluidized bed.

The ash container is provided with a wind box surrounding the vertical conduit within the ash container. An air distribution plate is spaced from the top of the ash container to form a wind box. In this way, the upper part of the ash container, the air distribution plate and the side wall of the ash container constitute a wind box. An air conduit provides access to the wind box through the wall of the ash container. The ash container section below the air distribution plate becomes the ash collection section. The bottom of the ash container is inverted conical, the lowest point of which connects to a vertical descending conduit with valve means.

The location of the air distribution plate and the direction of air flow through the ash collection chamber can minimize the risk that the air permeability of the air distribution plate will be obstructed by solids buildup.

[Preferred embodiment of the invention] Hereinafter, one embodiment of the ash classifier of the present invention will be described with reference to the accompanying drawings. However, the present invention is not limited to this.

FIG. 1 is a schematic diagram, including a partial cross section, of a fluidized bed reactor connected to an ash classifier of the present invention.

As shown, fluidized bed reactor 10 is connected to an ash classifier system 40 of the present invention.

The fluidized bed reactor 10 has a top wall 12, a side wall 14, and a bottom wall! Consists of 6. The bottom wall 16 is connected to the side wall 14 by a windbox wall 14a.

Fluidized bed reactor! An air distribution plate 18 is provided in the lower part of O,
A combustion chamber 28 above the air distribution plate is separated from a wind box 22 below the air distribution plate. Fluidized bed material 26 is used in combustion chamber 2
Place it on the top of the air distribution plate 18 in 8. A blower 34 is connected to the land box 22 by a conduit 32. The exhaust conduit 36 is connected to the upper part of the combustion chamber 28 and further connected to an external exhaust stack (not shown).

The ash classifier system consists of an ash vessel 50 located below the fluidized bed reactor 10 and a conduit system connecting the fluidized bed reactor to the ash vessel. The ash container has a top wall 56, side walls 58 and a bottom wall 62.

A downwardly sloping conduit 42 connects the lower part of the fluidized bed reactor lO directly above the air distribution plate 18 to the vertical classifier column 4.
Connect to 6. To control material flow through the conduit,
A valve 44 is provided in conduit 42. The vertical classifier column 46' extends downwardly through the top wall 56 of the ash container 50 to a midpoint between the top wall 56 and the bottom wall 62 of the ash container 50. The bottom wall 62 may have an inverted conical shape and is open at its lowest point to a vertically extending waste conduit 64. A porous air distribution plate 72 is provided within the ash container 50,
It is located between the top 56 of the ash container and the end 48 of the vertical classifier column 46. The air distribution plate 72 rests against the wall 58 of the ash container and divides the interior of the container into two parts: a wind box 74 surrounding the conduit 46 above the distribution plate 72 and a collection chamber 75 below the distribution plate 72. To divide. The wind box is connected by a conduit 76 to a blower 78.

Vertical classifier conduit 46 extends upwardly through junction 46a with conduit 42 to a point well above the level of the fluidized bed material in fluidized bed reactor 10. Classifier conduit 4
By providing a bend 52 of approximately I35@ at the upper end of 6, a return conduit 54 connecting this bend 52 and a return port 54a of the side wall 14 of the fluidized bed reactor 10 is extended diagonally downward.

During printing; -1-m-I of combustion chamber 28 of fluidized bed reactor lO Inside, the granular material body is supported on an air distribution plate 18 .

Air distribution plate 18 by blower 34 via conduit 32
Air is supplied to the lower land box 22. Air from the wind box 22 enters the fluidized bed material 26 through holes in the air distribution plate 18 and expands the fluidized bed to a significant height within the combustion chamber 28. The expanded fluidized bed material 26 has an obscured upper surface and a dilute concentration of very fine particles spread throughout the combustion chamber 28 , with some of these fine particles exiting the combustion chamber 28 through the exhaust conduit 36 . Fluidized bed material 26
When the temperature reaches a high temperature, the air introduced through the air distribution plate 18 acts as combustion air in the combustion chamber 28, and the fuel in the fluidized bed is combusted to generate combustion gas. Generally, the non-flammable ash component of the fuel is placed in a fluidized bed. They remain as ash particles, contact the incoming fuel particles, ignite them, and also function usefully as hot particles that help maintain the fluidized state of the fluidized bed. However, because the fine ash particles move continuously in the fluidized bed, they come into contact with each other and become incandescent at high temperatures, so that the fine softened particles agglomerate to a considerable extent. As these particles grow, they become less fluidizable and tend to descend lower down the fluidized bed and accumulate on the air distribution plate 18. Accumulation of these coarse particles on or near the air distribution plate 18 can result in fluidized bed deflow requirements, requiring shutdowns for maintenance, and increasing costs.

The ash classifier system 40 extracts a portion of the ash of various ignition gradations from the fluidized bed 26, separates the fine particles from the coarse particles, and returns the fine particles to the fluidized bed while maintaining fluidity. This is a system that can remove and dispose of coarse particles. Thus, a portion of the fluidized bed material can be withdrawn continuously or intermittently from the fluidized bed via the downwardly sloping conduit 42. The fluidized bed material, both coarse and fine particles, moves down an inclined conduit 42 with the amount of dilution being controlled by a valve 44. At the junction 46 a of conduits 42 and 46 , the fluidized bed material enters vertical classifier conduit 46 and descends vertically downward toward ash container 50 .

Air is introduced into the ash container windbox 74 via a conduit 76 by a blower 78 . Air flows from the wind box 74 into the holes in the air distribution plate 72. This air enters the ash recovery chamber 57 and flows vertically downward.

The only outlet for this air from collection chamber 57 is vertical classifier conduit 46. Thus, the air changes direction by 180 degrees at end 48 of conduit 46 and flows vertically upward. Thus, the air flow in the vertical classifier conduit 46 is in a countercurrent relationship to the flow of agglomerates and fine particles from the fluidized bed reactor.

The velocity of the air flow in the vertical classifier conduit 46 is
The speed is such that the descent of coarse ash particles and ash agglomerates within 6 is slow but unobstructed. Coarse ash particles and aggregates descend in countercurrent relation to the rising air and reach the collection chamber 57. However, the velocity of the air in conduit 46 is sufficient to clean the fine parts of the ash so that the fine particles are entrained in the air stream and flow upwardly. At the junction of conduits 46 and 44, the air and entrained fine particles take the course of least resistance and ascend continuously vertically. Once the air and fine particle flow reaches bend 52 at the top of vertical conduit 46,
It turns downward and flows into the return conduit 54. The conduit 54 continues to the combustion section 28 of the fluidized bed reactor IO via a return port 54a. Therefore, the fine particles are reintroduced into the fluidized bed 26, and the air entrained with the particles acts as additional combustion air in the combustion section 28.

The coarse ash aggregates descend into the collection chamber 57 and collect in the bottom 62 of the ash container and waste conduit 64. From time to time, valve 68 is opened to remove a portion of the coarse agglomerate and discard it.

In a typical operation, coal particles having an average diameter of 3/4 inch or less are introduced into a fluidized bed reactor and combusted. The ash particles and agglomerates produced in the reactor and removed from the fluidized bed vary in size, ranging from very fine to (regular) particles, and agglomerates ranging in size from very fine to (regular) particles. This includes those with a diameter of 1 inch or more. Generally, it is desirable to return ash particles having an average diameter of less than about 1/4 inch to the fluidized bed reactor. Also, the air flow feeding the ash container windbox is adjusted to obtain the air velocity in the vertical classification 4 conduit necessary to obtain the desired classification.

It should be noted that providing the air distribution plate 72 near the top of the ash container 50 has the very significant advantage that the holes in the distribution plate are less likely to be clogged by fluidized bed material. be. In other words, the first
Generally, no solid objects come into contact with this distribution plate. and secondly, the air flow straight down through the holes in the distribution plate prevents the distribution plate from approaching the particles and the distribution plate 72
Stray particles that may come into contact with or accumulate can be quickly removed.

Although the invention has been described in terms of preferred embodiments, those skilled in the art will readily appreciate that modifications and changes can be made without departing from the spirit and scope of the invention. Such modifications and changes are also included within the scope of the invention and the claims.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram, including a partial cross section, of a fluidized bed reactor connected to an ash classifier of the present invention. In FIG. 1, 10 is a fluidized bed reactor, 12 is an upper wall, 1
4 is a side wall, 16 is a bottom wall, 18 is an air distribution plate, 22 is a wind box, 28 is a combustion chamber, 34 is a blower, 14o is an ash classifier, 42, 46 and 54 are conduits, 44 is a valve, 50 is ash container, 52 is a bend, 56 is an upper wall, 5
7 is a recovery chamber, 58 is a side wall, 62 is a bottom wall, 72 is an air distribution plate, and 74 is a wind box.

Claims (8)

[Claims] (1) In an ash classifier for a fluidized bed reactor, a first
a downwardly sloping conduit for receiving the bed material, a second substantially vertical classifier conduit connected to the first conduit receiving the bed material, an ash container having a top wall and a bottom wall; extending a conduit through the top wall and into the ash container;
a perforated air distribution plate located below the top wall of the ash container and substantially above the bottom wall, and between the top wall of the ash container and the end of the second conduit within the ash container; , the area between the upper wall and the air distribution plate constitutes a wind box, and the second conduit extends vertically above the connection with the first conduit to control the flow in the fluidized bed reactor. extending to a point located above the plane of the bed material, and forming a bend at the highest point of the second conduit, extending the second conduit obliquely downward from this highest point, and forming an opening in the fluidized bed reactor. An ash classifier, characterized in that the ash classifier is connected to a combustion section of the fluidized bed reactor to return a flow of fine particles and air to the combustion section of the fluidized bed reactor. (2) The ash classifier according to claim 1, wherein the first conduit is provided with means for controlling the flow of fluidized bed material from the reactor. (3) The ash classifier according to claim 2, wherein the means is a slide valve. (4) The area between the wind box and the bottom wall constitutes an ash recovery chamber, and a conduit means is provided for recovering accumulated ash from the recovery chamber. Ash classifier as described in section. (5) Claim 4, characterized in that the conduit means is provided with a valve for controlling the flow of ash from the collection chamber.
Ash classifier as described in section. (6) providing an ash container with a top wall, side walls, and a bottom wall, and providing a substantially vertical conduit through the top wall and above the bottom wall that is capable of receiving a gravity flow of ash particles and aggregates; a substantially horizontal perforated air distribution plate extending into the ash container, surrounding the vertical conduit and abutting the side wall, between the top wall and the end of the vertical conduit; The area between the wall and the distribution plate defines a wind box, the area between the wind box and the bottom wall defines an ash collection chamber, and means for introducing a flow of air into the wind box are provided. By providing air from the windbox flows downwardly into the ash collection chamber through the porous air distribution plate and then redirecting this air flow to counter-current the flow of ash particles and aggregates. An ash classifier system characterized in that the ash is allowed to flow upwardly through the vertical conduit. (7) The ash classifier system according to claim 6, further comprising a conduit for extracting ash from the ash recovery chamber through its bottom wall. (8) The ash classifier system according to claim 7, wherein the conduit means is provided with a valve for controlling the speed at which the ash is taken out.